This project utilizes extant data that were collected as part of the NIH-funded New England Children's Amalgam Trial (NECAT, N=534) to help fill knowledge gaps in the potential for bisphenol A (BPA) related negative health effects of dental composites in children. In addition to extant data, new clinical trial data on children (N=110) receiving their first dental composite restorations (the same material used in NECAT) will be collected to investigate associations with urinary BPA levels, both within-person over time and in comparison to children receiving the clinic's standard restorative material, amalgam. Children have higher levels of urinary BPA than all other age groups in the U.S. Meanwhile, the most common chronic disease in U.S. children is dental caries. Composite restorations are rapidly becoming the preferred treatment for caries in children, with over 10 million composite restorations placed each year in children under the age of 14 yr in the U.S. While experiments have concluded that BPA is released in the short term following the initial placement of materials, research in this area has neglected the fact that composites degrade over time, thereby creating potential for chronic, low doses of chemicals to be released over the life of the restoration or sealant. The prevailing paradigm that chemicals released from composites have no health effects must be challenged, and this study responds to nationwide calls for research to identify the human health impact of BPA exposures using extant data from a vulnerable human population group - children from pre puberty through adolescence. This project uses both the randomized controlled trial design and prospective cohort methodologies to test hypotheses regarding composites exposure among children aged 6-10 at baseline with 5 yr of follow-up. The BPA related measurable health outcomes to be tested are: weight gain (including 5-yr changes in body mass index, body fat percentage, and lean body mass, N=534), neuropsychosocial problems (including validated measures of behavior, emotional, and personal adjustment problems, visual-motor abilities, memory index, and IQ; N=534), and an exploratory sub study (n=66) of immune function changes. NECAT used standard approved dental composite materials, which have been found to release BPA, have estrogenicity and/or cytotoxicity in vitro and in vivo experiments. This project will measure urinary BPA in a new sample of children to determine the composite's effects on urinary BPA over time. Detailed data on the timing of composites placement, replacement, and repair, including type of material (composite, compomer, preventive resin restorations, or sealants) and sizes of restorations, at the level of the tooth surface, were recorded at semi-annual dental visits. Analyses to be conducted include intent-to-treat (testing total composite restorations exposure vs. amalgam) and dose-response models (testing individual composite materials using various exposure measures). NECAT obtained in-depth information on potential covariates annually, providing a unique, ethical, and efficient opportunity to examine the human health impact of dental composites in children.